Driver for red Luxeon Rebel triple?

I want to build a light with Luxeon Rebel triple. Probably in a S3 or a S2+ host (sometimes I wish for a version for 20mm drivers).
For now I plan to use standard AMC7135 driver with modded firmware, but given the huge disparity between the Vbat and Vf of the LED, I’m looking for a more optimal solution.
So either a buck driver for parallel triple or a low-current (the Rebels are rated 700mA) boost driver for serial setup.
Or maybe the losses in the linear driver even in this situation are still not large enough for the extra effort of locating a different type of driver?

I’m not familiar with that type of driver, but did use a lineair driver to drive a red led. And yes it hurts a bit that you ditch half the power via the 7135 chips, but it works alright. I did make an effort to make good physical contact between the driver ground ring and the flashlight body to guide away the heat from the chips, but that should be easy with the S3/S2+.

In one (far) red Rebel AA-size light I have run it on a LiFePO4 battery, its lower voltage makes it easier on the 7135’s. You can get them in 18650 size as well.

I have seen the AMC7135’s hit thermal shutdown on a single XMLColor (red channel) at one amp in free air. Knock a couple of tenths off a fully charged battery and the regulation goes away. So like djozz says, a good ground and/or heatsink is absolutely required.

You might try emailing support at luxeonstar.com and asking — I’ve found the folks there quite responsive to questions several times, and they know what they’re selling.
(If you do get more information please follow up here, I’m very interested in what you decide and how it works out — one of these days, I want to try a triple PC Rebel with red-orange, red, and far red, and another with amber, red-orange, and red, or something along those lines)

I’ve built a couple Luxeon rebel triples and quads lately.
Red Luxeon Rebel Triple

My red convoy S2+ triple is running on a Qlite driver with four extra chips stacked for a total of 4.5A. That’s 1.5A per emitter, and the red rebels handle it quite easily. Even Luxeon says they can be driven harder if appropriate heat sinking is in place. Mind you, I got my rebels from Luxeon Star, which is the only place I know of that sells them on custom direct thermal path sinkpads.

I also built a quad cyan rebel M1, also on DTP SinkPad. I’m driving this one with a FET driver. I use a non hi-drain cell in this light (NCR18650A) and get 8A on turbo. 2A per emitter, and it seems quite happy.

For a Convoy tube light, think the 7235 linear driver with four extra chips is right at the sweet spot with 1.5A per LED.

I just today made a shorty S2+ triple with red Nichia 219B’s. I used a 3A lineair driver. See the what did you mod today thread.

If the 7135 will suffer from overheating too much I’ll definitely consider using LiFePO4’s for it.

With my bad habit of using too much solder and 100W iron on hand, soldering the driver very thoroughly probably won’t be a problem. Maybe will fill the rest of the driver cavity thermal silicone or basic thermal paste.

Sure.
Do you want to make this “Three Shades of Red” for any specific purpose or just for the art of it? :slight_smile:

Thank you for the link. I see that wiring the SinkPad in parallel will require some manual dexterity. Using PTFE wires is a good idea, though common locally available ones are too thin for this current.
EDIT: just realized that with three pairs of wires, normal 0,12 sq.mm wire size should be sufficient. The only problem left is that they are colorless and it’s impossible to make the coloring stick to to the teflon insulation. So have to be extra careful when soldering them to the pads.
I think that 4,5A total is a bit too much for this light (Just how much 650nm RED do you comfortably need? :slight_smile: ). Initially I planned to use only single LED, but with spare parts available for triple build and insignificant price difference between single+shipping vs triple+shipping I decided to do a triple anyways.
For now I plan to use standard 8x7135 driver with 2,8A (with low modes working through one 7135) and 3x7135 for testing

Thank you for the input. Red Nichia 219Bs are pretty exotic. And I never even heard about them before looking at your build. What kind of lighted tail do you plan to make?

basically to have a somewhat wider range of wavelengths

Also looking at trying these three emitters as a triple from luxeonstar.com

These specific model numbers are pretty close in electrical demand, so ought to work in series
(I want to try series first, before tangling with trying to wire up three in parallel, as my work gets sloppy at small scales, a bit shaky)
(Xref, I asked about this idea a while back at Host suggestions for the 20mm Noctigon Triple - #7 by hank — just getting around to trying it)

Red - 75 lm (LXML-PD01-0040)
Red-Orange - 90 lm (LXML-PH01-0050)
Amber - 77 lm (LXML-PL01-0040)

I’m not sure how much these overlap the eye’s receptors, but I think the result might be better color perception than with a monochrome red source.

You do have options in wiring them up in parallel.

The Holy trinity

Or

The home run.

Although the home run is a bit fussy, it may also be easier for you as only one pair of wires need to come up through the center from the driver.

Those are helpful pictures, thanks.

This started with Xoden’s original question about what drivers to consider for a triple

I don’t know if Xoden was asking about a driver for serial or a driver for parallel emitters.
People don’t always specify which they mean.

I have trouble imagining getting that first (six-wire setup) soldered to — to where? — on the driver side.

Do people make up a “wiring harness” before trying to nail it all down?

Series might be the way to go. Three Luxeon Rebel Red @ 2.8V each would give you 8.4V which corresponds nicely with 2S Li-Ion cells! Use a linear driver with Zener mod, and you’ve got it! You might need to choose a different host, though.

I soldered two thicker gauge wires from the drivers neg and pos…then attached them to a little PCB I made onto which I attached the two sets of thinner wires.


Aside EDIT with link — Luxeonstar.com triples on SinkPad2 boards come from a Canadian supplier and shipping to the US costs.

I just noticed that LEDSupply offers some comparable choices (and free shipping for lightweight packages)

Note that LEDSupply doesn’t offer the choice of voltage bins for the colored Rebels so it’s a bit more of a gamble if you mix colors.

The mcpcbs at LEDsupply aren’t direct thermal path.

thanks ouchyfoot, important difference noted.

(My last order from Luxeonstar was for this triple combination, matched as closely as possible — so not picking the very brightest of each color, but the closest electrical characteristics, to run serial)
Red - 75 lm (LXML-PD01-0040)
Red-Orange - 90 lm (LXML-PH01-0050)
Amber - 77 lm (LXML-PL01-0040)

Haven’t put it together yet, but I think I’ll use a simple qlite 3A driver first, not push it hard.

Make sure you post beamshots when you’re done.
I’m thinking of a quad with two cyan and two blue. Hoping for a peacocky teal

Got to wrestle with parallel wiring. Tedious, with shaky hands.
I need a minion. Or a robot. Or waldos …

The very first part of This thread will show the easiest was to wire a triple parallel.

Yep. Somehow while I wasn’t paying attention, I got old and my hands started shaking.
It happens.

That’s why I was looking for a serial driver for the triples, or a parallel board
(the KD nichia triples that come on a parallel board are so-o-o easy to use)

But I digress. Back to red Rebel drivers ….

Parallel of course. I want a reasonably compact light and decided to use Convoy S2+ host.
And the smallest boost driver for single18650 cell I was able to find is 20mm. If you are aware of any boost drivers that can fit S2+ I would be really thankful for the suggestion.
Or a host suitable for triple and which can fit 20mm driver.